Strand holder and dam for prestressed concrete molds



Jan. 1, 1963 r I T 33 I 53 53 a6 T. J. BELLE 3,070,867

STRAND HOLDER AND DAM FOR PRESTRESSED CONCRETE MOLDS Filed Dec. 21, 1959 5 Sheets-Sheet 1 II T T U L- 6 62 INVENTOR.

711500025 J BELLE ATTORNEY T. J. BELLE Jan. 1, 1963 5 Sheets-Sheet 2 Filed Dec. 21 1959 INVENTOR. filaono/ae JBELL;

AITTORNV T. J. BELLE Jan. 1, 1963 STRAND HOLDER AND DAM FOR PRESTRESSED CONCRETE MOLDS 5 Sheets-Sheet Filed Dec. 21, 1959 INVENTOR. FIEODOREJ BELLE BY 3? r ATTORNEY STRAND HOLDER AND DAM FOR PRESTRESSED CONCRETE MOLDS Filed Dec. 21, 1959 T. J. BELLE Jan. 1, 1963 5 Sheets-Sheet 4 INVENTOR. THEODORE Ll. BELLE ATTORNEY T. J. BELLE Jan. 1 1963 STRAND HOLDER AND DAM FOR PRESTRESSED CONCRETE MOLDS Filed Dec. 21, 1959 5. Sheets-Sheet 5 IN V EN TOR. 7745000195 J- BELLE A 7' TORWEY United States Patent 3,070,867 STRAND HOLDER AND DAM FOR PRESTRESSED CONCRETE MOLDS Theodore J. Belle, 4245 SW. 15th St., Miami, Fla. Filed Dec. 21, 1959, Ser. No. 860,832 6 Claims. (Cl. 25-118) This invention relates to manufacturing precast and prestressed concrete beams and other related products used in the construction building industry and more particularly to improvements in and relating to apparatus for producing such forms as pilings, double T slabs, beams, girders and the like.

The particular improvement which constitutes this invention comprises a novel form of combination strand holder and dam which serves as a stop divider in the casting of such prestressed concrete products and which is readily installed with a minimum of labor and easily removed after the concrete is hardened and set.

The combination removable strand holder and stop dam divider of this invention is reusable again and again, is practically indestructible and has an extremely long life of usability.

This device is much more efficient in use than any heretofore known in the art and forms a perfect divider seal and dam against the flow of liquid concrete while holding the reinforcing strands of woven wire, which are under high tension, in the required position.

It is well known in the art of casting prestressed concrete pilings, beams, and the like, whether in single or double T or other forms, that the common practice is to employ a casting bed and associated form of great length, at least 300 feet long and frequently much longer. The reinforcing strands of prestressed woven wire cable generally extend the entire length of the form. The length of each section of each piling or other piece being cast is determined by inserting dams set crosswise in the form at the desired intervals in a manner which leaves a gap of about a foot in length. Thus each length of piling, beam, double T or other form being cast lies end to end and a large number of them may be formed in one pouring or casting operation. This invention contemplates the use of a limitless variety of forms, for example, octagonal shaped stop dams may be used.

The wet or plastic concrete must be prevented from running over into the spaces which are designed to separate the ends of each piling or other piece being cast. In the past this operation has been attempted by the use of wooden cross dams which have not proven to be very efiicien-t. A certain amount of leakage of wet concrete generally occurs frequently in amounts great enough to ruin the end of the piling or other object being cast.

These wooden dams have to be hand made which requires much carpenter labor and are hence expensive. They do not serve to support the wire strands very well. They can only be used once since they stick to the concrete and the wire strands and have to be destroyed to be removed after each casting operation.

Another problem which is present in the use of the hand made wooden dams is that the prestressed wire strands mus-t be cut in the middle of the space formed by the wooden dams between the pilings or other object being cast and then again flush with the end of each piling making three cutting operations at each separation point. Considering that the normal strand used is A to A" in diameter and that each is of woven steel and many strands are used in each object being cast, six or more being the usual minimum number, and that the cutting is usually done with a welding torch, it readily is apparent that the cutting operation is a costly operation.

It is an object of this invention .to overcome the difficulties and inefiiciences of the present practice' some 3,070,867 Patented Jan. 1, 1963 "Ice of which are described hereinbefore, by providing a permanent, reusable strand holder and stop dam which will afford great saving in use, reduce waste and aid in producing a better product in the art of producing precast prestressed concrete products.

This and other objects of the present invention are accomplished by the design and creation of novel apparatus as set forth in the following detailed description and accompanying drawings in which:

FIGURE 1 is a front view of the upper portion of a square form of the stop-dam divider of this invention before assembly.

FIGURE 2 is a cross section of a casting bed illustrating the lower portion of a square form of the stop dam divider of this invention resting on the casting bed with the strand separation plates in position and the strands located in the grooves of the separation plates.

FIGURE 3 is a cross section of a square form of the divider illustrating the upper and lower portions thereof assembled together in operative association on a casting bed with the side plates of the casting form in position and the strand separation plates in operative position.

FIGURE 4 is a broken top view of a casting bed illustrating the stop-dam divider of this invention mounted in operative position therein and showing the end plates of the casting form and the longitudinally extending strands bolted in position under tension and ready for casting.

FIGURE 5 is a perspective view of the upper portion of the square form of stop-dam divider of this invention.

FIGURE 6 is a perspective view of the strand separation plates of this invention illustrating the strands located in the slots of the separation plates which they will occupy.

FIGURE 7 is a perspective view of the lower portion of the stop-dam divider.

FIGURE 8 is a cross section of the upper portion of the divider taken on the line 88 of FIGURE 5.

FIGURE 9 is a front view of one of the strand separation plates. FIGURE 10 is a cross sectional view of the lower portion of the stop-dam divider taken on the line 10-10 of FIGURE 7.

FIGURE 11 is a perspective view of another form of stop-darn divider of this invention used in producing a concrete form known as a double T.

FIGURE 12 is a perspective view of the strand separat-ion plate used in conjunction with the double T stopdam divider illustrated in FIGURE 11 and shown' 10 cated in operative position in a portion of a casting form with the strands in position for casting.

FIGURE 13 is a perspective view .of the top spacer member v FIGURE 14 is a perspective view of a portion of the casting form used in the production of double Ts illustrating a pair of the stop-dam dividers located in position for casting and showing the longitudinally extending strands of cable in position under tension ready for casting.

FIGURE 15 is a top view of one of the double T. form of stop-dam dividers shown in FIGURES l1 and 14.

. FIGURE 16 is a longitudinal cross section of the double T stop-dam divider taken in the line 1616 of FIGURE 15.

FIGURE 17 is a similar longitudinal cross section of the double T stop-dam divider taken on the same line as that of FIGURE 16 but showing the strand separation plate inserted in operative position therein.

FIGURE 18 is a longitudinal cross section of the double T stop-dam divider taken on the line 18-18 of FIGURE 17 showing the strand separation plate in operative position therein. 7 I J FIGURE 19 is a side elevation of the double T strand separation plate shown in FIGURES 17 and 18,

FIGURE 20 is a perspective view of the double T separation plate, and,

FIGURE 21 is a cross section of a double 1' beam.

Referring now to the drawings in detail one form of the stop-dam divider of this invention is designed particularly for use in casting prestressed concrete pilings and is illustrated in FIGURES 1 through of the drawings. This form comprises a hollow approximately square shaped box like member indicated generally by the numeral 25 and comprises three principal parts, namely, an upper portion 26, a lower portion 27 and a plurality of cable strand separation plates 28.

These three principal parts are shown in assembled relation in FIGURE 3 and in exploded relation in the series of three FIGURES 5, 6, and 7 respectively and are made of cast aluminum, steel or other desired material or may be molded of hard rubber.

The purpose and function of the stop-dam dividing device 25 of this invention is three fold. When in assembled relation in the casting bed 60 with side plates 64 fixed in position in any suitable well known manner, as shown in FIGURES 3 and 4, the device acts as a stop and dam to prevent the flow of any plastic wet concrete beyond the end point which has been predetermined for the length of the pile or other object being cast. The precise close fit and novel design of the parts prevents any leakage of wet concrete. The second function of the novel design of this invention is the locking of the pre-tensioned steel woven wire cable strands 33 in the exact desired position during pouring of the wet concrete and subsequent hardening. The third function is the easy separability of the three major parts 26, 27, and 28 of the device of this invention after the concrete has set and hardened. Thus the entire stop-dam dividing device 25 of this invention is immediately and readily re-usable.

Referring in more detail to the three principal parts of this invention, the upper portion 26, lower portion 27, and the several cable strand separation plates 28 which are designated to be easily and readily assembled to form the stop-darn dividing device 25 and as easily disassembled it will be noted that the box-like upper portion 26 has two approximately square sides 26', see FIGURE 5. These sides are joined together by relatively narrower end members 36 and a top member 37 of similar width to form the square shaped hollow box-like upper portion 26. is preferably accomplished by a casting operation, using aluminum or steel or rubber molding so that the upper portion of the device 25 is one piece or integral. Qross members 38 may be formed or fixed between the sides 26" at the lower open end of the box 26 for reinforcing supports and it will be noted that the lower portion of the end members 36-depend below the lower edge of the sides 26' of the box 26 as do the cross members 38 for the purpose of engaging the lower portion 27 of the stop-dam divider device in assembly as will be hereinafter described.

' Vertically extending slots 40 are provided in each of the sides 26' of the upper portion 26 of the stop-dam divider box 25 to slidably receive the cable strand separation plates 28 and to permit the cable strands 33 to extend through the box 25. Three of such slots 40 and cable strand separation plates 28 are shown in the form for casting ,pillings illustrated in the drawings but any desired number may be employed depending on the number of reenforcing tensioned cable strands desired.

The relatively shallow lower portion 27 of the box 25 comprises side members 27' ends 41 and a bottom 42. Each of the sides 27 has notches 43 formed in the upper edges of the side members which are in alignment with the vertical slots 40 of the upper portion 26 of the stop-dam box 25 and adapted to receive the lower strands of cable 33 when the upper and lower portions 26 and 27 are assembled in operative relationship together with the 4 strand separation plates 28 as particularly well shown in FIGURES 2 and 3 of the drawings.

The lower portion 27 of the box is placed in the casting bed 60, as the first step in the assembly operation, as shown in FIG. 2 and FIG; 3. The pre-tensioned steel woven Wire cable strands 33 are then strung out loosely along the entire length of the casting bed 60. After this is done, the strand holding separation plates are then placed in vertical position with their lower ends inserted within the lower portion 27 of the box 25. See FIGS. 2 and 3. The lengthwise extending cables 33 are then inserted in the central grooves 52 and strung over and under the shoulders 51, all in operative supporting engagement therewith. Thus each strand is supported in position for subsequent tensioning. Thereafter, the upper portion 26 of the hollow box 25 is slid down over the vertical strand holder separation plates 28, thus locking the cable strands in place, as shown in FIG. 3. The upper hollow portion 26 of box 25, of FIG. 5, as shown in the exploded view of FIGS. 5, 6 and 7 is thus brought down over the cable strand holders 28, of FIG. 6, and into locking engagement with the lower hollow portion 27 of the box 25,

, as shown in FIG. 7. This is also illustrated in FIG. 1,

showing the upper portion 26 of the box 25, which will be slipped down over the lower portion 27 of the boxl25, as shown in FIG. 2, moving downwardly in the direction indicated by the arrow, to encompass the vertically upstand ing separating strand holder plates 28, which are shown in FIG. 2, having the cable strands 33 mounted in operative position. The result of this telescoping of the upper portion of the box 25 over the strand holders 28 and into final operative position is illustrated in FIG. 3.

The cable strand separation plates 28, as clearly shown in FIGURES 2, 6, and 9, have two widths, thicknesses and lengths for the purpose of performing the dual function of supporting and maintaining the highly tensioned cable strands in the desired position and preventing any leakage of plastic wet concrete through the slots 40 when the three principal portions 26, 27, and 28 of the stop-dam device 25 of this invention is assembled in operative position. The portion 48 of each separation plate 28 is of the exact width as the hollow space or inner cross dimension between the sides 26' of the upper portion 26 of the device, and the sides 27' of the lower portion 27, which cross dimensions are identical, thus providing a snug fit from one inner surface to the other of the side plates 26' of the upper portion 26 of the box 25 when slid into posi- 7 tion. The length of each portion 48 of each plate 28 is sufficient to extend vertically upwardly within the upper portion. 26 of box 25 beyond and above the top of each slot 40 and to depend downwardly within the lower portion 27 of the box 25 below the notches 43 thereof.

Widenthicker and shorter portion 50, of each cable strand separation plate 28 is formed integrally with the portion 48 just described preferably by being cast in-- tegrally therewith or the portion 56 may be fixed to the: portion 48 by welding or other suitable means. The purpose and function of each portion 50' is to exactly fit within and fill the slots 40 of the upper portion 26 to pre-- vent any leakage of plastic or wet cement when the pilings. are being cast and to provide upper and lower shoulders. 51 and a central groove 52 to support the cable strands 33 in exactly the desired spaced relation as shown in the drawings. To achieve this purpose the portions 50 of each strand support and separator plate 28 are the exact thickness of the width of the slots 40 and are of a width whereby they extend through the slots 40 which are formed in each side 26' of the upper portion 26 of the stop-dam divider box 25 just exactly far enough so that the outer edges of each portion 50 is flush with the outer surfaces of the sides 26' of the upper portion 26 of the box 25'. Thus when assembled the cable strands 33 rest on the upper and lower shoulders of the outermost separator plates 28, as well as in the central groove 52 of each of them. In the form illustrated in the drawings the central one of thethreeplatesZSdoes not have a groove 52 since no central cable strand is being used. It is understood however that more or less cable strands in a particular job would require more or less grooves 52. The piling being cast and shown for the purpose of illustration is set up for eight woven wire cable strands although more or less might be used.

In casting prestressed concrete pilings, beams, or other shapes it is well known in the art that the common practice is to employ a casting bed 60 and associated form of great length, at least 300 feet long or longer. The reenforcing strands 33 are .generally of woven steel cable and extend the entire length of the form. In FIGURE 4 there is illustrated a top view of such a form. The strands 33 pass through and are fixed to end plates 61 at each end of the 300-foot-long form by outer bolts and nuts 62 or other suitable gripping means by which the strands 33 are initially stretched and placed under great tension. In the form used for illustrative purposes in the drawings the casting bed 60 is first laid down extending the entire length of the form.

Then with the cable strands all in place and under tension stop-dam divider devices 25 of this invention are mounted in place on the casting bed 60 at the desired intervals determined for the length of piling to be cast. If for example each piling is to be 12 feet long one of the devices is installed at every twelve feet.

It is clear from the above description and the accompanying drawings how this may be accomplished with First the lower portion 27 is placed along the entire length of the piling to be formed on the casting bed 60 by sliding it under the lower three cable strands 33 as shown in FIGURE 2. The lower three strands rest in the grooves or notches 43 which are formed in the top edges of the sides 27 of the member 27.

Next the lower ends 48 of the cable strand separation plates 28 are placed vertically within the lower portion 27 of the device 25 and arranged with the upper and lowermos-t cable strands 33 abutting the shoulders 51 of the outermost strand separation plates 28 and with the outermost middle strands passing through the grooves 52 of the plate. The upper and lower center strands 33 rest on and abut the shoulders 51 of the center separation plate 28 all as clearly shown in the drawings, particularly FIG- URES 2 and 6 thereof.

With the lower portion 27 of the device 25 and the strand separation plates thus in place the upper portion 26 is then lowered in place to complete the assembly of the stop-dam divider ready for casting. The upper portion slides downwardly over the separation plates in the manner of a hood and the lower edges of the sides 26 rest squarely upon the upper edges of the sides 27' as shown in FIGURE 3.

The widened portions 50 of the separation plates 28 slidably engage and fill the slots so that no possible leakage of plastic or wet cement can occur. It will be noted that by making the slots 40' to fit the thickness of the cable strands 33 no leakage is possible at the points where the strands pass through the side walls ofv the stopdam divider.

The last assembly operation is the mounting of side plates 64 which are secured to the sides of the'casting bed in any suitable well known manner. The corners of the form made up of the side plates 64 and casting bed are beveled to provide a beveled edge on the finished piling but any other desired shape may be used.

A suitable hook eye 65 may be formed integral with the top of the upper portion 26' of the device of this invention to assist handling if desired.

After the concrete has set and hardened all that is necessary to disassemble the stop-dam divider of this invention is to remove the side plates 64 from the casting bed 6%) and lift the top portion 26' and lift out the separation plates 28. The lower row of strands 33 are then cut in the center and after the piling is removed the lower portion 27' may be removed. They come out easily and clean leaving the'ends of the concrete pilings smooth. Breakage and cracking and other destructive etfects of leakage are avoided and great savings in labor and material is efiected as the devices may be used over again repeatedly. Heretofore employed methods require the constant rebuilding of wooden forms which require much labor to construct and install and are destroyed in the removal process. Also many castings are marred and unusable due to leakage damage.

Another labor saving and cost reducing factor in the use of this invention which is of great importance and never heretofore attainable in the present practice of casting prestressed concrete pilingsand other shapes and forms lies in the cutting of the cable strands by burning with a welding torch as heretofore mentioned. In the present practice the hand made wooden dams must be built about a foot apart between the ends of each piling. This requires three cutting operations on each cable, one in the middle of the space between each of the present known wooden dams to permit separation of the ends of each section of piling permitting access to the wooden forms so that they may be taken apart and removed from the cable strands they surround. This leaves an extension .of cable strand end of up to .siX inches protruding from each piling end. Thus each strand must be again burned through so their ends will be flush with the ends of the piling. This requires three cutting burning operations on each cable strand. If eight cables are used as is shown here and is common that means twenty-four cutting operations by burning with a welding torch.

The stop-dam and strand holder device hereinabove described may be extremely narrow from side to side approximately three inches or less since it is accurately cast or molded and since its novel design permits assembly and disassembly without requiring much space be tween the ends of each piling to be formed. Thus since the center cutting is not required to separate the pilings to get at the old wooden forms for purposes of removal, that cutting operation is always eliminated. In most installations of the device of this invention the space between [the side plates may be so narrow that a single cutting operation is sufficient to burn the cable ends ofi flush to the end of each piling.

Thus in the form of piling illustrated herein the twentyfour separate cutting operations presently required with the welding torch in known methods are always reduced to eight. When the number of twelve-foot pilings formed in one operation'using the conventional 300 foot casting bed it is apparent that the reduction in cost of producing pilings by the use of this invention is enormous.

The second form of this invention illustrated in FIG- URES 11 through 21 is for use in the casting of the structural prestressed concerete form well known in the building trade as a double T, a cross sectionof one of such finished shapes 66 being illustrated in FIGURE 21 of the drawings.

Essentially this form of the invention has the same general purpose and function as that-just described for use in the production of pilings namely to provide a permanent reusable stop-dam and cable strand holder which is easily and readily assembled and installed and affords great savings in use and results in a better product- FIGURE 14 illustrates a section of a casting bed 6.7 for making double Ts 66 and shows the longitudinally extending cable strands 68, there being five in number in the form used for illustration. The stop-dam strand holders indicated generally by [the numeral as used to produce double Ts are shown mounted in operative position in the double T casting bed 67', partly in dot-ted lines, in FIGURE 14.

The numeral 71 indicates the place, see FIGURE 14, where the cable strands 68 are deflected by well known means, usually by hydraulic jacks (not shown). This deflecting operation is performed after the cable strands have been placed under longitudinal tension, by suitable omes? well known means. Both the lengthwise longitudinal Stretching and subsequent deflecting of the woven steel Wirecable strands 68 in the double T form, and 33 in the form for making pilings previously described, form no part ofthis invention and are well known in the art of form prestressed concrete shapes and forms.

The casting bed 67 has two deep fairly wide substantially vertical V-shaped channels 72, see FIGURE 14, which curve at the top to form a fiat horizontal surface 73 extending outwardly from each channel 72 to the outer edge of the form which is bordered by an upstanding flange 74 extending along each edge the length of the casting bed 67. A fiat horizontal portion 75 connects the V-channels 72.

The V-channels 72 extend the entire length of the casting bed and since the double T concrete forms to be cast will be of any desired length, for example 10, 15, or feet, and it is the common practice to pour the wet concrete along the entire 300 feet or more of the casting bed at one time, the stop-dam cable strand holders 70 will be installed in pairs, one in each V-channel 72 at the desired intervals. The purpose and function being to stop the flow of the wet or plastic concrete without leakage at the selected intervals and to support the cable strands at such points.

The stop-dam strand holder 70 of this form of the invention comprises essentially two parts; one is a hollow casting of aluminum, steel, or other suitable material, or which may be molded from rubber, having two side pieces70' shaped to snugly fit within the V-shaped channels 72 and each side piece having a vertical cable strand receiving slot 80. See FIG. 11. The side pieces 70' are connected by a pair of integrally formed vertically disposed plates 81 which extend from the inner surface of one side piece 79" to the other and are cast integrally with the side pieces as is a cross wise extending top member 82. The top member 82 has a rectangular shaped hole 83 formed therein which is of the width of the distance between the inner surfaces of the vertically disposed plates 81. See FIGURES ll, l5, l6, and 17.

A cable strand holding and separating plate 85, shown in FIGURES 12, l7, 18, 19, and 20 of the drawings, is of two widths and thicknesses. This plate 85 is preferably .an integral one piece casting having a portion 86 of the exact width to extend from one inner surface of one of the side pieces 70 to the inner surface of the other and be vertically slidable therein. The other portion 86 of the plate 85 being as wide as the distance between the outer surfaces of the side pieces 78'. This portion 87 is of a thickness which permits it to slidably fit within the groove 80 in a snug manner to prevent any passage or leakage of plastic wet cement. The width of the portion 86 being sufficient to extend from the outer surface of one of the side pieces 76' through the slots 80 formed in each side piece, to the outer surface of the opposite side piece 70' so that the outer side edges of the portion 87 will be flush with the outer surfaces of the side pieces 70' of the approximately V-shaped stopdam 70 and thus produce a smooth surface at the end of each double T shape 66 which is cast.

The wider portion 87 of the vertically disposed cable strand holding and separating plate 85 has grooves 90 formed in said wider portions 87 which extend from edge to edge horizontally cross-wise thereof to receive and support the prestressed tensioned cable strands 68.

v Vertically projecting members 91 extend upwardly through the holes 83 formed in the top member 82 of the stop-dam 70. u-shaped channel members 92 are designed to extend cross-Wise of the casting bed 67 and are adapted to be cooperatively associated with each pair of stop-dams 70 to complete the casting form for the double T shape 66. 'These U-shaped members have holes 93 in alignment with the holes 83 of the stop-dams 70 adapted to receive the vertically projecting members 91. The U-sh'aped channels are installed with the open portion of the channel extending downwardly and the channel is just wide enough to encompass the upper portion of each of the pair of stop-dams as shown in FIGURES l4, l6, l7, and '18 and so complete the assembly.

The extreme upper end of the members 91 which project upwardly to the holes 83 are provided with a hole 94, as clearly shown in FIGURES l9 and 20, through which a wedge member 95, see FIGURES 17 and 18, is inserted to lock the assembly into position.

Thus it will be seen that the cable strands extend through the slots of the sides 70 of each stop-dam 70, which slots 80 are approximately the width of the cable strands and provide a snug fit between the slot 80 and each cable 68. Since the wider portions 87 of the cable strand holding and separating plate extend through and completely fill all of the rest of the slot 80 it is apparent that no leakage of plastic wet cement can occur when the device is assembled as disclosed.

It will be apparent that from the design of the novel form of stop-darn of this invention no wet or plastic concrete can enter the form during the pouring operation either from the top or the sides of the stop-dam and no leakage can occur from any direction beyond the stopdam.

The device of this invention provides a novel design and arrangement of parts for the purpose and function set forth which is readily assembled and disassembled, and may be re-used over and over again and is practically indestructible. It provides the same great savings in time, labor and material as does the first described form and substantially reduces the cost of producing double T forms of prestressed concrete.

Having thus described this invention, -I claim:

1. A stop-dam divider and strand holdsr for use in the casting and production of pie-stressed pre-cast concrete pilings and other structural forms comprising a hollow box shaped upper portion having a plurality of vertically disposed slots in the sides thereof adapted to permit the passage of longitudinally extending tensioned strands therethrough, a plurality of strand holding members adapted to slidably fit within said slots being wide enough to extend from one side of said box shaped upper portion to the other side in a manner whereby the outer side edges of said strand holding members are flu-sh with the outer sides of the box when the strand holders are in assembled relation therewith, each strand holder having a plurality of horizontally extending strand receiving slots and shoulders adapted to receive and support a tensioned strand, each strand holder being of a thickness nearly equal to the width of the slots of the upper box portion whereby to close the slots and prevent passage of liquid or plastic concrete therethrough, and a lower box shaped portion adapted to fit exactly together with the upper portion when placed in assembled relation with the upper portion and the strand holding members in a manner to prevent the flow or passage of liquid or plastic concrete beyond the stop-dam.

2. A stop-darn divider and strand holder apparatus for use in combination with relatively long casting beds in the production of prestressed precast concrete pilings and other structural forms which apparatus comprises a separable two-part box having an upper box portion and a lower box portion, a plurality of strand supporting members which fit slidably within the confines of both the upper and lower box portions, said upper box portion and lower box portion and strand holders being adapted for ready assembly in operative position on the casting bed, said strand supporting members having horizontally disposed notches therein adapted to support longitudinally disposed metal strands which extend lengthwise of the casting bed before the concrete is poured, said upper box portion and lower box portion being fitted at their lower and upper open ends respectively in a manner to permit ready assembly before the concrete is poured and ready disassembly after the concrete has set and hardened, said upper box portion and lower box portion, which comprise the stop dam divider, having vertical elongated slots adapted to permit passage of said metal strands therethrough, said strand supporting members being adapted to extend through said vertical slots and adapted to close said slots throughout their length excepting only that portion through which the metal strands extend, the open portion approximating the thickness of the strands which extend therethrough thereby to prevent the fiow of wet concrete beyond the side walls of the upper box portion and lower box portion of the stop dam divider, said strand supporting members having projecting tongue-like portions which extend from the upper box portion through the inner box portion to facilitate the assembly of the two-part section to form the enclosure box.

3. A stop-dam divider and strand holder combination as described in claim 2 wherein the several parts are of the exact dimensions required to assure ready repeated assembly and disassembly and provide a close fit with bottom and sides of the casting bed in a manner to prevent leakage of wet or plastic concrete.

4. The combination of a stop-dam divider and a strand support for use in producing reinforced prestressed concrete structural forms which comprises separable upper and lower hollow box shaped stop-dam divider members, both upper and lower box shaped dividers having slots therein the width of the strands to be used and a plurality of vertically disposed strand supporting members which fit within said both upper and lower box-like hollow dam members and are adapted to support said strands which extend through said slots in a manner to seal the slots of the hollow darn members against leakage of wet fluid concrete, all of the members of said combination being designed to be readily and accurately assembled and placed in operative position with the ends of said vertically disposed strand supporting members extending into 10 both the upper and lower boxes as connecting members, in an elongated mold before pouring of the wet concrete and readily disassembled by separation of the upper and lower hollow stop darn divider members when the concrete has set and hardened without damage to any of the parts of the combination.

5. A combination stop-dam and strand holder apparatus as described in claim 1 where in the sides of the box shaped housing are spaced apart sufiiciently to permit easy access to the strands for cutting the strands after the concrete has set and hardened and the stop-dam and strand holder apparatus has been removed but are close enough together to require only two cutting operations of the strands to produce a commercially desirable product.

6. A combination stop-dam and strand holder apparatus as described in claim 1 wherein the sides of the box shaped housing are spaced apart sufficienily to permit easy access to the strands for cutting the strands after the concrete has set and hardened and the stop-dam and strand holder appartus has been removed but are close enough to gether to require only one cutting operation of the strands to produce a commercially desirable product.

References (Iited in the file of this patent UNITED STATES PATENTS 1,460,403 Bondi July 3, 1923 1,770,219 Shakespeare July 8, 1930 FOREIGN PATENTS 130,113 Australia Nov. 18, 1948 700,497 Great Britain Dec. 2, 1953 700,947 Great Britain Dec. 16, 1953 702,562 Great Britain J an. 20, 1954 708,062 Great Britain Apr. 28, 1954 90,435 Norway Nov. 18, 1957 

1. A STOP-DAM DIVIDER AND STRAND HOLDER FOR USE IN THE CASTING AND PRODUCTION OF PRE-STRESSED PRE-CAST CONCRETE PILINGS AND OTHER STRUCTURAL FORMS COMPRISING A HOLLOW BOX SHAPED UPPER PORTION HAVING A PLURALITY OF VERTICALLY DISPOSED SLOTS IN THE SIDES THEREOF ADAPTED TO PERMIT THE PASSAGE OF LONGITUDINALLY EXTENDING TENSIONED STRANDS THERETHROUGH, A PLURALITY OF STRAND HOLDING MEMBERS ADAPTED TO SLIDABLY FIT WITHIN SAID SLOTS BEING WIDE ENOUGH TO EXTEND FROM ONE SIDE OF SAID BOX SHAPED UPPER PORTION TO THE OTHER SIDE IN A MANNER WHEREBY THE OUTER SIDE EDGES OF SAID STRAND HOLDING MEMBERS ARE FLUSH WITH THE OUTER SIDES OF THE BOX WHEN THE STRAND HOLDERS ARE IN ASSEMBLED RELATION THEREWITH, EACH STRAND HOLDER HAVING A PLURALITY OF HORIZONTALLY EXTENDING STRAND RECEIVING SLOTS AND SHOULDERS ADAPTED TO RECEIVE AND SUPPORT A TENSIONED STRAND, EACH STRAND HOLDER BEING OF A THICKNESS NEARLY EQUAL TO THE WIDTH OF THE SLOTS OF THE UPPER BOX PORTION WHEREBY TO CLOSE THE SLOTS AND PREVENT PASSAGE OF LIQUID OR PLASTIC CONCRETE THERETHROUGH, AND A LOWER BOX SHAPED PORTION ADAPTED TO FIT EXACTLY TOGETHER WITH THE UPPER PORTION WHEN PLACED IN ASSEMBLED RELATION WITH THE UPPER PORTION AND THE STRAND HOLDING MEMBERS IN A MANNER TO PREVENT THE FLOW OR PASSAGE OF LIQUID OR PLASTIC CONCRETE BEYOND THE STOP-DAM. 